In prior U.S. Pat. No. 4,233,996, assigned to the assignee herein, there is described a tobacco leaf processing operation wherein the tobacco leaf is simultaneously subjected to cuts perpendicular to one another to form tobacco particles of cigarette rod-forming dimensions, the tobacco particles resulting from the cutting operations are air classified to remove the heavier particles having stem associated therewith from the lighter lamina particles, the heavier particles usually are threshed to separate the stem from lamina particles connected thereto, and the lamina particles resulting from the threshing usually are mixed with the lighter lamina particles resulting from the classification to provide tobacco particles which are suitable for direct formation of cigarettes therefrom without the necessity for further shredding or shred shortening operations.
The mass of tobacco shreds which results from the cutting step must be disentangled prior to air classification. The disentangling operation can lead to shortening of some of the tobacco shreds as a result of the pressures applied to the shreds as they are drawn apart. Shortening of the tobacco shreds decreases the filling power of the tobacco, and this is undesirable. Further, the threshing operation requires multiple threshing and separation to effect complete separation of the lamina material from stem, and these steps create much dust and many particles which are not suitable for subsequent cutting and use in finished cigarettes.